kebutuhan tantalum di dunia semakin meningkat,sedangkan sumber utama tantalu bukan dari tambang-tambang,melainkan dari timah.contohnya penyediaan tantalum untuk USA,sumber utamanya beasal dari terak timah Thailand,Afrika dan Bolivia.
Coalbedmethane is increasingly playing a major role as a gas resource in the United States, Presently, about eight percent of the total annual natural gas produced in the United States is coalbed methane (fig. I). Coalbed methane was originally thought to be economicallyproduced only from high-rank coal. However,with the advent of economic coalbed …